Valve mechanism



March 14, 1939. NOBLE 2,150,808

- VALVE MECHANISM I Filed June 1; 1955 IN VEN TOR.

2270mm [VoZZe BY ,4. W

A TTORNEY Patented Mar. 14, 1939 PATENT OFFICE VALVE MECHANISM Warren Noble, Michigan City, Ind., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application June 1,

Claims.

This invention relates to valve mechanisms, and more particularly 'to improvements in valve springs for use with annular disc Valves of the type commonlyused for automatically controlling 5 intake and discharge of fluid'with respect to the cylinders of air compressors or pumps.

Valves of the flat ring type are well known, and comprise a fiat annulus, which may be either flexible or rigid, guided axially and limited as to lift by suitable overhanging structurethe lift of the valve being opposed by one ormoresprings which may be helical, spiral or ring-like in form. Hitherto, valve springs of the ring type have been made from fiat steel, formed first as a plane washer and later bent to arcuate form so that the tips of the arc, or lips at the ends of the arc, abut the surface of the valve, and the center of the arc abuts the guard or stop structure which limits the lift. The advantages of this formof valve spring are sufficient to make its use very general. It occupies a minimum of space, is simply made, and may be laminated for any desired strength and to make for reliability. It suffers the disability that in'it a portion'of its bulk is utilized as active material and the inevitable unequal distribution of stress tends to some unreliability, though in general it is very satisfactory. At the expense of simplicity of fabrication, the durability and action of such springs may be improved by making either the inside or outside of the spring washer elliptical and bending the latter suitably with respect to the axes of the ellipse to provide the valve and stop abutments, but at the best the stress distribution is imperfeet, and remains unfavorable to great continuity of service. It is well known to those skilled in the art that the reliability of such springs is materially affected by the degree of surface polish, and especially by the perfection of finish on the edges. By concentration upon mechanical perfection, vast improvement has been made. The unequal distribution of stress in the material, however, remains as a deteriorating influence, casting the shadow of uncertainty on spring life.

This invention has for one of its objects the provision of an improved valve-spring, and a primary aspect thereof involves the substitution for the rectangular-section, ring-type spring, of one of circular cross section, similarly bent into arcuate form for contacting with the valve and 50 stop surfaces, and located by any suitable means between the valve and stop surfaces. As the spring quality invoked has its being through torsional stress in the section; and as: this cannot exist unequally within the confines of a toroid, all the material involved in a spring of the Ill 1935, Serial No. 24,569

proved type mentioned is unequally stressed, a condition enabling a sufliciency of spring action to be obtained with lower fibre stress iri the material from which the spring is made. For any desired strength of spring the minimum possible fibre stress is thus automatically achieved. As the form is such as to be especially easy to fabricate free of surface defects, an approach to complete reliability has been opened and the space and weight characteristics of the spring both improved. Further objects of the invention are to provide an improved valve element and an improved guard element with which the'improved spring may coact, and a still further object is to provide an improved valve mechanism comprising the improved spring and valve elements herein described in illustrative forms. Other objects and advantages of the invention will hereinafter more fully appearin the course of'the following description and as more particularly pointed out in the appended claims.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

In this drawing,

Fig, '1 is a central section through a compressor or pump valve mechanism embodying the illustrative form of the invention.

Fig. 2 is a perspective view of the improved valve spring.

Fig. 3 is a plan view of the valve stop or guard.

Fig. 4 is a cross sectional view taken on line 4-4 of Fig. 3.

Fig.-5 is a plan view of a. valve.

Fig. 6 is a cross sectional view taken on line 6-6 of Fig; 5.

Fig. 7 is an elevational view of the improved valve spring;

In this illustrative embodiment of the invention the improved valve mechanism is shown associated with a compressor or pump cylinder member shown at I having a liner 2 and a cooperating head member 3. Within the head member a chamber 4 is formed which is divided into difierent portions by valve cage elements later described. One of these portions communicates through an opening 5 with the bore of the cylinder, while another portion communicates through a passage 6 with the discharge space of the compressor cylinder.

The valve mechanism comprises a pair of cage or seat elements I and 8, the element 1 being the inlet valve seat element and the element 8, the discharge valve seat element. These valve seat elements are held in position by a stud 9 threaded at it) within the cylinder l, and having improved tween the chordal tips, of the spring unloaded (i. e. bent) and the diameter of the circular form respectively designated l3, in the case of the inlet cage element, and II in the case of the discharge cage element. The inlet valve seat or cage element 1 has a valve seat I5 formed thereon surrounding a port I6. An improved valve ll, of comparatively thin,'flexible metal, is associated with the seat and normally held in closed position by a transversely bowed annular spring I8 of an'improved form. .The spring l8 and valve I! are guided during movement by guiding wings ls formed integral with the valve seat element 1. Similarly, the discharge seat or cage element is provided with an annular port 20, surrounded by a valve seat 2|, with which an annular valve 22 cooperates. The valve 22 is yieldingly seated by a valvespring. 23 likewise of' improved form, guided by guiding wings 24 formed integral with the valve seat element 8. 'Mounted in spaced relation to each of the valves mentioned above is an improved valve guards 25 and 26 are secured to the guiding wings I9 and 24 of the valve seat elements 1 and 8 by screws 21.

As previously mentioned, the valve springs l8 and 23 are of improved form, each having a circular cross section. Such a valve spring, having been, prior to arcuate formation, a circular ring, may, in compressed condition, be completely located within a circular groove or recess, which recess it 'will only partially fill in its unloaded (flexed) position. The diiference in distance be-' from which the spring is bent, is actually very small, so that the slight incompleteness of guiding thus occasioned is not detrimental to the valve action. The slight float between the seating surfaces on the valve proper and the cooperative seat surfaces of :the valve cage element is definitely beneficial and does much to prolong the life of both seatand valve.

The ring of spring wire which constitutes the improved spring appears at first sight to be a simple form, easy to manufacture. There are, however, certain metallurgical difiiculties in the way of makinga perfect ring of uniform metallic structure, notably due to the disinclination of the higher carbon steels, (such as .are used for spring-making) to weld successfully The forming of a ringand welding its ends as at 28 in 1 Fig. 7 to make it continuous is thereforesubject'to the danger that the carbon content of the steel will be burned out during the welding and the sectionof the ring including the weld therefore have poorer physical characteristics than the remainder of the circle. Provided the spring is not too highly stressed and the welding flash and adjacent surfaces properly cleaned and polished, the dissimilarity of metallic structure engendered is not very important, but if in the search for lightness and economy of space (subscribing to better characteristics for the compressor or pump) the steel of the ring is stressed The portions of the.

. article.

aims-(e well up in its elastic range, danger exists that the yield point of the resultant metal in weld-deteriorated section may be approached. In order to avoid this, such springs are better made from steel Wire or low carbon content, formed, welded into a continuous ring, bent to arcuate contour and then carburized by being heated in a carburizing box or in a hot retort in an atmosphere ofgas rich in carbon, the latter being perhaps the more desirable method for this particular Subsequent to the permeatiol'i of the surface of the ring with the additional carbon (to any desired depth, or if necessary completely through the section) it is finally polished, reheated in a neutral atmosphere, quenched and drawn. A homogeneous metallic structure, without danger of weakness in the weld zone, is thus achieved.

There are other practical ways of making such springs. High carbon Wire may be welded in a nitrogen atmospherewithout marked deterioration at the weld. Again, it is known that hy' drogen brazing satisfactorily joins the adjacent ends of ring hoops. In this case, however, despite the penetration of the steel structure by the copper, the joint remains as a section of the brazing metal inferior in physical characteristics to the steel. Obviously rings may be cut off a high carbon steel tube in a turning machine by the use of suitable forming tools, polished on separate machines and hardened in the ordinary course of events. Danger of occlusions in the original tube wall'casts shadow upon the probable reliability of springs so made. 'In order to avoid some of this trouble a small ring expanded in rolls to provide planishing of the surface and' partial elimination of any direct transverse occlusion strand may be used.

The forming of the ring from low carbon steel wire, welding the hoop, eliminating the mechanical traces of the weld,bending to arcuate form, carburlzing in a gas atmosphere with the spring continuously moving, repolishing, reheating in a neutral atmosphere, quenching, drawing, and

washer or annulus. Here the valve itself becomes part of the spring system and by reason of its form suffers the disabilities which the circular section ring spring avoid. superior reliability, therefore, it is necessary to take away from the valve element any self springing action and substitute the ability for selflocation in order that the dual function of springing and guiding may be allocated to the single Wire ring. However, flexibility on the part of the valve, in a radial direction, is beneficial, so that the valves I1 and 22 are made by adding a relatively deep annular groove or channel '29 (as distinct from a bead) midway between the outer and'inner peripheries of the valve ring. With this provision the valve can be formed from lightgauge material and the desired general planar stiffness readily achieved, the upstanding profile of the'channel remote from the valve face providing the necessary locating means for a ring spring and abutment surface for a limit stop.

In constructing for.

The provision of the annular corrugation moreover provides a radial flexibility capable of taking care of slight variations in the manufacture and wear of both the valve and its seats, and for this reason it is desirable to use only a central corrugation, avoiding upturning of the valve edges and additional stifiness in the neighborhood of the valve seats. As installed in a compressor the major co-nvexities of the corrugations are always compassed by the higher pressure. The suction valve has thus the corrugation extending into the clearance space in the cylinder; the discharge valve is installed with the convexity of the corrugation on the receiver side of the valve. The pressure surrounding the corrugation is thus tending to reduce the angles between the adjacent valve faces from its designed 180 relation to an angle of less than 180, forcing the lips of the valve to the seats despite the fact that the valve as a whole is materially stiffer than it would be without the corrugation. Whilein theory any corrugation or head would perform the same function, it is found to be best to make a corrugation of suflicient depth to exceed the radius cornprehending the difference between the radii of its inner and outer peripheries, as the maximum flexibility is so obtained. Any desired flexibility may be achieved by giving greater or less depth to the corrugation, and as an end result there is attained a valve made of light material stiff enough to permit finish of its face and possessing a degree of self-adjustment important in practice.

The form of the guard is best seen in Figs. 3 and 4, and it will be noted the guard has a lobed opening therethrough to promote flow, has a peripheral flange to act as a stop, and is dished to provide a shoulder which will cooperate in locating the spring. Obviously, due to its dishin and flanged construction it may be made of relatively light, sheet material.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the invention is shown for purposes of illustration only and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, a valve comprising thin, uniformly spaced seating portions disposed in a common plane and connected by a corrugation, a valve seat having spaced seat-providing surfaces respectively engageable by said seating portions, a valve guard comprising a metallic plate having flow orifices inside its periphery and a portion projecting towards said valve seat and constituting a valve stop and engageable by said corrugation on said valve on opening movement of the latter, and a spring round in radial section and comprising a single continuous loop flexed out of a plane and engaging said valve and guard and coacting with said corrugation and with said projection.

2. In combination, a valve comprising thin, uniformly spaced, annular seating portions disposed in a common plane and connected by an annular corrugation, a valve seat having spaced seat-providing surfaces respectively engageable by said seating portions, a circular valve guard comprising a dished metallic plate having flow orifices inside its periphery, and, outside said orifices, a peripheral rim constituting a valve stop and engageable by said corrugation on valve-opening movement, and a flexed annular spring of round stock and of a conformation flattenable substantially to unit spring-stock thickness and coacting With said corrugation and with said rim.

3. In combination, annular concentric valve seats, an annular valve cooperating therewith, a transversely-bowed annular, single loop spring round in radial section, said annular valve having a medial projection from its non-seating surface coacting with said spring in the positioning of the valve, and a valve guard comprising a plate having an annular projection to cooperate with said medial projection on said valve to limit valve opening and ported to permit flow within its periphery.

4. In combination, a valve cage having valve seats thereon, guiding wings formed integral with said valve cage, a valve cooperating with said valve seats and having uniformly spaced seating portions disposed in a common plane and con nected by a corrugation, a valve guard attached to said guiding Wings and having a peripheral projection which extends toward said valve and is engage-able by said valve corrugation on valve opening movement, a flexed annular single-loop spring round in raidal cross section and formed of round spring stock of the same cross section as the radial cross section of said spring, said spring engaging said valve and valve guard and positioned by said corrugation and said valve guard projection, said valve on opening movement guided by said guiding wings.

5. A valve mechanism comprising, in combination, a valve seat member, a valve cooperating therewith, a valve guard, and an annular valve spring arranged between said guard and valve comprising a single endless loop and of round radial section, and transversely bowed, said spring flattenable substantially to unit spring-stock thickness whenthe valve is unseated.

WARREN NOBLE. 

